As information capacity increases, in not only the communication field including a trunk line and an access system but also information processing in a router and a server, the optical interconnection technology using an optical signal has been developed. Particularly, to use light for short distance signal transmission between or in boards in a router and a server device, an optical waveguide, which has a higher flexibility of wiring and can more highly densify wiring compared with an optical fiber, is desirably used as an optical transmission channel. More particularly, an optical waveguide formed by using a polymer material with excellent processability and economic efficiency shows promise.
Such an optical waveguide is formed by, for example, curing and forming a lower clad layer, forming a core pattern on the lower clad layer, and then laminating an upper clad layer to the core pattern as described in Patent Document 1. Then, an optical waveguide in which a mirror is formed on the laminated body by cutting is proposed.
In such an optical waveguide, a light signal with an optical path changed by the mirror passes through the substrate, and thus the substrate should be a material with a high transmissivity to a light signal. Furthermore, when a space exists between the substrate and an optical device, the spot diameter of a light signal with an optical path changed by the mirror increases, causing the optical transmission loss to deteriorate.
As an optical waveguide with a less space between the substrate and an optical device, for example, an optical waveguide with a mirror in which an opening hole is provided on the core or at the ends of the core and in which a component for changing an optical path is inserted to the opening hole is proposed as described in Patent Document 2.
However, the work to produce such an optical wave guide is complicated because the component for changing an optical path is required to be inserted in each optical path changing part of the optical waveguide. Moreover, highly accurate alignment is necessary because the alignment is required in the planar direction and the vertical direction of the substrate.